Up to
half the patients with colorectal cancer develop metastases,
and the commonest site for metastases is the liver. The
peculiarity of the portal venous system means that not infrequently
the liver is the first and only site of stage IV disease.
Although the understanding from most cancers is that stage
IV disease carries a poor prognosis and management is thus
geared towards palliation, there is increasing evidence
that the picture is quite different for stage IV colorectal
cancer when metastases are found only in the liver.
At present, liver resection is considered the gold standard
of treatment for metastases from colorectal cancer that
are confined to the liver. Surgery offers the best results,
with 5-year and 10-year survival rates of up to 45% and
21%, respectively. By comparison, 5-y survival is less than
5% and median survival about 6 to 9 months if surgery is
not possible.
Work-up for metastases
The aim of follow-up in colorectal cancer patients is thus
to detect recurrences early, when these are still potentially
confined to the liver. The role of tests for carcinogenic
embryonic antigen (CEA) and ultrasonography in follow-up
is well established. When a lesion is suspected, a triphasic
CT scan is required for assessment of operability and planning
of the operation. In addition, there should be extensive
work-up to exclude extrahepatic disease. Such investigation
includes CT or PET-CT of the thorax, brain, and bone.
Assessment for surgery
The criteria for liver resection used to be three or fewer
lesions, with the largest smaller than 3 cm and confined
to one lobe of the liver. Today, irrespective of size, number,
and extent of lesions, surgical resection may be offered
to patients (1) with adequate hepatic reserve, (2) with
no extrahepatic metastases, and (3) in whom a 1 cm tumour-free
margin is achievable.
Several factors are associated with a better survival rate
after liver resection for colorectal metastases and these
are taken into consideration in the decisions about surgery.
These factors include (1) colorectal primary at N0-N1 stage,
(2) largest metastasis less than 7 cm in diameter, (3) postoperative
normalising of serum CEA level post-operatively (in patients
whose preoperative CEA were elevated >4 ng/dl) (4) wedge
instead of lobar resection. Negative prognostic factors
include (1) signs and symptoms of extra-hepatic metastases,
(2) substantially raised CEA level, (3) more than 6 lymph
nodes involved in the primary lesion, (4) a satellite pattern
of metastases in the liver, (5) bilobar hepatic disease,
(6) likelihood of a positive resection margin, (7) extrahepatic
nodal involvement, and (8) poorly differentiated primary
tumour.
Results of surgery
Liver resection is fairly safe and postoperative mortality
rates of less than 2% are reported in well-established hepatobiliary
units. In addition, morbidity rates are generally less than
10% and usually relate to minor problems, such as wound
infection. Survival rates are up to 70% at 3 years, up to
45% at 5 years, and up to 21% at 10 years.
Although colorectal cancer metastases to the liver is stage
IV disease, the results with surgical resection suggest
that perhaps we should begin to look at this subset of patients
with “curative” intent rather than relegate
them to “palliative” therapy.
A/P London Lucien Ooi
Head
Surgical Oncology
